Electric discharge lamp



April 13, 1937. G, JENKINS L 2,076,725

ELECTRIC DISCHARGE LAMP Filed Feb. 25, 1935 BY /ZZQRNEY Patented Apr. 13, 1937 UNITED STATES,

2,076,725 ELECTRIC mscmuten LAMP Henry G. Jenkins and John w. Ryde, Middlesex,

England, assignors to General Electric Company, a corporation of New York Application February 23, 1935, Serial No. 7,922 In Great Britain February 23, 1934 3 Claims.

lene separated from the main body of the tube by a porous plus. 1

Theobject of the, present invention is to pro-f vide a gaseous electric discharge lamp device of the above type which is of a more simple structure and which is more effective in various. instances 20 than prior devices. Still further objects and advantages attaching to the device and to its use and operation willbe apparent to those skilled in the art 'from the following particular description. We have discovered that, it anthracene is used 25 insteadof naphthalene, it canbe placedin the main part of the tube and need not be separated from the discharge by a porous plug. At the same.

a time metal (for example iron) electrodes can be used in place of the graphite electrodes described in the British Patent 349,261. Also when anthracene is used it is easier to obtain a satisfactory ripple efiect, that is a wandering of the luminous column over the cross-sectionv oi the tube when the main" gas filling is neon (giving red light) than when naphthalene is .used.

According to the'invention in lamps of the type specified the said means is a substance preferably anthracene, placed in the mainbody of the lamp, that is tosay, so that its vapor has substantially unobstructed access to the region throughv which the discharge passes.

when the main ng is neon, the anthracene may be deposited on the walls of the tube near- 45 one or both electrodes. The electrodesare bonibarded in the usual way to free them from gas; anthracene is then distilled into the main tube from-a side tube, which may then be sealed oil.

The pressure 01' the neon is preferably -40 a When the main filling is a mixture of argon and *mercury the anthracene may be placed in a small open glass container, loose in the main -.tu be, but retained in the, neighbourhood of the 55 electrodes by}; constriction in the main tube.

Againit is preferably introduced from a side tube after bombardment.

In either case cylindricaliron electrodes may beused. But while, according ,to the invention, it is 5 necessary that the vapor of anthracene or the like should have free access to the discharge it is not desirable that the discharge should have free access to the solid from which the vapor is generated; For, if it has, the solid willbe black- 1-0 ened. Thus the main part of the solid, and even flakes of it, must be prevented from reaching the space between the electrodes. Further, since the discharge sometimes extends behind the electrodes in the absence of an obstruction, although it may not be visible there, it is desirable to place between the region where the solid is situated and the region between the electrodes an obstruction which, whiiepermitting the substantially free access of the vapor, hinders the pas- 2o sage of the solid or of the discharge. The access of the vapor is to be regarded as substantially free if the vapor pressure of the substance during operation in the region between the electrodes is not so much less than the equilibrium vapor pressure corresponding to the temperature of the solid that the appearance of the discharge is different from what it would be if the vapor pressure were the said equilibrium pressure.

ln the drawing accompanying and forming part of this specification two embodiments of the ing vention are shown, in which Fig. 1 is a side, sectional view of one end of alamp device during the manufacture thereof and embodying the present invention,

Fig. 2 is a plan view of one element of the embodiment of the invention illustrated in Fig. 1,

Fig. 3 is a planview of another element of-the embodiment ofthe invention illustrated in Fig. 1,

1 Fig. 4' is a side, sectional view of one end of another embodiment of the invention during the manufacture thereof, and

Fig. 5 is a side elevational view of a completed gaseous electric discharge device embodying the invention, one end of which is shown in Fig, 1.

site the centre of the electrode 2. The space surrounding this electrode, into which the constriction opens is partially closed at each end by mica plates 8, 9. The plate 8, shown in Figure 2,

5 is a complete disc pierced with two holes l0, through which pass the leading-in-wires 4. The plate 8 thus nearly closes the end of the cylinder 2 adjacent to the pinch. 9 is an annulus supported round 2 by strips of metal H turned back 10 out of the cylinder 2, see Fig. 3. The outer edge of the annulus 9 has notches I! to permit the free passageof vapor while restricting the passage of the discharge or of the solid material. After the electrodes have been de-gassed in the is usual way, anthracene is distilled into the space between 8 and 9 and then I is sealed off.

By slight modifications of this arrangement the temperature that the anthracene attains during operation, and therefore the vapor pressure, may

be controlled. Thus if the lamp is to be used in a cold situation and it is desired to keep the anthracene as hot as possible, the constriction I may be placednearer theend of theelectro'de remote from the pinch (which is the hotter end) and the disc 8 replaced by an "annular washer similar to 9 just on the pinch side of the constriction. If, on the other hand, it is desired to keep the anthracene cool, 9 and 1 may be displaced towards the pinch: or 9 may be abolished entirely and I placed between B and the pinch; suilicient space must then be left between 8 and the envelope and/or the cylinder 2 to allow the vapor to pass. The cool position is generally preferably for blue ripple tubes (filled with a mixture of mercury and argon); for red ripple tubes (filled with neon) a higher temperature is usually required.

In Figure 4 the constriction l is onthe side of 2 remote'from the pinch and opens into the space 40 between the main envelope I and an inner tube I3, sealed to l at one end It, but free from it at the other so as to leave an annular opening l5 through which the vapor can pass freely. I3 is constricted at its central portion l6. Anthracene is distilled into the space surrounding this constriction and 1 sealed ofl. Itis there warmed by the heat developed by the discharge passing through the constriction; its temperature can be raised further by surrounding the tube with .lag-

ging. Of course lagging can be used to adjust the temperature or the solid also in the lamp shown in Figure l or even when there is no obstructlon between the solid and the discharge.

The method of manufacturing tubes according to the invention needs no special description. The electrodes are de-gassed' by a discharge through a mixture of neon and helium in the usual way. When they are free from gas, the lamp is completely evacuated and the anthracene distilled into the main envelope, and the constrictions sealed oil, with the pump still in operation. If a red ripple tube 'is required in a lamp of the kind shown in Figure 1 or 4, neon is introduced to a pressure of about 10' mm.; if a blue ripple tube is required, argon is introduced to a pressure of about 5 mm. together with a globule of mercury. A complete lamp of the type illustrat in Fig. 1 is shown in Fig. 5.

No special ageing process is necessary, but the full ripple efiect usually is not developed until the lamp has been in normal operation for some hours.

What we claim as new and desire to secure by Letters Patent of the United States is:--

1. An electric discharge device comprising an envelope having iron electrodes sealed therein and containing a discharge supporting gas, said envelope having a source of anthracene vapor therein for introducing a stream of said impurity into the discharge path between said electrodes, said impurity producing a ripple discharge in said gas.

2. An electric discharge device comprising an envelope having electrodes sealed therein and containing a discharge supporting gas, said envelope having a source of anthracene vapor for introducing a stream of said vapor into the discharge path between said electrodes, said anthracene vapor producing a ripple discharge in said.

gas.

3. An electric discharge device comprising an elongated tubular envelope having the same external diameter throughout its length, electrodes sealed therein and a discharge supporting gas therein and a source of anthracene vapor therein for introducing a stream of said vapor into the discharge path between said electrodes, means mountedalong the discharge path between said electrodes in said envelope and interposed between said path and said source to protect said source from the discharge between said electrodes, said vapor producing a ripple discharge in said 8&8.

HENRY G. JENHNS. JOHN W. RYDE. 

